Display device

ABSTRACT

A display device includes: a gate line having an extension direction; a switch unit electrically connecting to the gate line; a pixel electrode electrically connecting to the switch unit; and a slit in the pixel electrode, wherein a virtual line parallel to the extension direction passes through an end point of the slit which is closest to the gate line, the pixel electrode is divided into a first portion and a second portion by the virtual line, and the first portion is closer to the gate line than the second portion, and wherein the slit has a first width in the extension direction and a second width in the extension direction, the second width is closer to the first portion than the first width, and the first width is less than the second width.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefits of the Taiwan Pat. Application Serial No. 104110840, filed on Apr. 2, 2015, the subject matter of which is incorporated herein by reference.

This application is a continuation (CA) of U.S. Pat. application No. 17/370,359, filed Jul. 8, 2021, Pat. application No. 17/370,359 is a continuation of U.S. Pat. application No. 16/919,164, filed Jul. 2, 2020, U.S. Pat. application No. 16/919,164 is a division of U.S. Pat. application No. 15/878,639, filed Jan. 24, 2018, U.S. Pat. application No. 15/878,639 is a continuation of U.S. Pat. application No. 14/817,289, filed Aug. 4, 2015, and each of which is incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The embodiments relate to a display panel and, more particularly, to a display panel that the pixel electrode near to the contact via has a specific pattern to improve the liquid-crystal efficiency.

2. Description of Related Art

In recent years, all the display devices are developed toward having small volume, thin thickness and light weight as the display techniques progresses. A liquid crystal display (LCD) device is a flat panel display device with a thin thickness, so a conventional cathode ray tube (CRT) display is gradually replaced by the LCD device. Especially, the LCD device can be applied to various fields. For example, the daily used devices such as cell phones, notebooks, video cameras, cameras, music players, navigation devices, and televisions are equipped with liquid crystal display (LCD) panels.

For the conventional LCD device, a liquid crystal layer is disposed on a pixel electrode, and voltage is applied onto the pixel electrode to control the tilt of liquid crystal molecules. Thus, it is possible to control light from a backlight module disposed below the LCD panel to pass or not pass through the liquid crystal layer, and the purpose of displaying can be achieved. In addition, the purpose of displaying different colors can be achieved through the pixel units.

Even though the techniques of the LCD device are getting matured, many manufacturers are desired to develop LCD panels having improved display quality thereof to meet the consumers' requirements. Hence, it is desirable to provide a display panel with improved display quality to satisfy the requirement for high display quality.

SUMMARY

The present disclosure provides a display device, comprising: a gate line having an extension direction; a switch unit electrically connecting to the gate line; a pixel electrode electrically connecting to the switch unit; and a slit in the pixel electrode, wherein a virtual line parallel to the extension direction passes through an end point of the slit which is closest to the gate line, the pixel electrode is divided into a first portion and a second portion by the virtual line, and the first portion is closer to the gate line than the second portion, and wherein the slit has a first width in the extension direction and a second width in the extension direction, the second width is closer to the first portion than the first width, and the first width is less than the second width.

Other objects, advantages, and novel features of the embodiments will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a display device according to one embodiment;

FIG. 2 is a cross-sectional view of a display device according to one embodiment;

FIG. 3 is a top view of a first substrate according to one embodiment;

FIG. 4 is a cross-sectional view of a first substrate according to one embodiment;

FIGS. 5 and 6 are respectively a schematic view of partial pixel electrode according to one embodiment;

FIG. 7 is a diagram showing the relation between a driving voltage to a display panel and the efficiency of a liquid crystal layer according to one embodiment; and

FIG. 8 is a simulation result showing a bright state of a display panel according to one embodiment.

DETAILED DESCRIPTION

The embodiments have been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Furthermore, the ordinal numbers such as “first”, “second” and “third” used in the present specification and the appended claims are used to modify the units in the appended claims. The ordinal numbers themselves do not mean or represent the claimed units having ordinal numbers, and do not represent the order of one claimed unit to another claimed unit or the sequence of the manufacturing process. The ordinal numbers are used only for naming one claimed unit to clearly distinguish the claimed unit from the other claimed unit having the same term.

FIG. 1 is a cross-sectional view of a display device according to one embodiment. The display device of the present embodiment comprises a backlight module 1 with a first polarizer 2, a display panel 3, and a second polarizer 4 sequentially disposed thereon. Herein, the display panel 3 of the present embodiment comprises: a first substrate 31, a second substrate 33, and a display medium 32 between the first substrate 31 and the second substrate 33. In the present embodiment, the first substrate 31 can be a thin film transistor (TFT) substrate comprising TFT units (not shown in the figure) as switch units; and the second substrate 33 can be a color filter (CF) substrate comprising a CF layer (not shown in the figure). However, in other embodiment, the CF layer (not shown in the figure) may be comprised in the first substrate 31; in this case, the first substrate 31 is a color filter on array (COA) substrate. In addition, in the present embodiment, the display medium 32 is a liquid crystal layer known in the art.

FIG. 2 is a cross-sectional view of a display device according to one embodiment. Herein, the first substrate 31 of the present embodiment comprises a substrate 311 with a TFT layer 312, a common electrode layer 313, a first insulating layer 314, a pixel electrode layer 315 and a first alignment layer 316 sequentially disposed thereon. Herein, the TFT layer 312 comprises plural TFT units (not shown in the figure) as switch units, and the pixel electrode layer 315 comprises plural pixel electrode (not shown in the figure). In addition, the second substrate 33 comprises another substrate 331 with a CF layer 332 and a second alignment layer 333 disposed thereon. Furthermore, the display medium 32 is disposed between the first alignment layer 316 and the second alignment layer 333 in the present embodiment. Herein, the substrates 311, 331 can be made of any material for substrates generally used in the art, such as glass, plastic or other flexible materials; the common electrode layer 313 and the pixel electrode layer 315 can be made of any material for transparent conductive electrodes such as ITO, IZO or ITZO; the first insulating layer 314 can be made of any insulating material generally used in the art such as oxides, nitrides or nitrogen oxides; and the first alignment layer 316 and the second alignment layer 333 can be made of any alignment layer material generally used in the art such as polyimide (PI), followed by performing an alignment layer process (such as rubbing process or photo-alignment process) thereon.

Hereinafter, the structures of the pixel electrodes on the first substrate 31 shown in FIGS. 1 and 2 are illustrated in detail.

FIGS. 3 and 4 are respectively a top view and a cross-sectional view of a first substrate according to one embodiment. As shown in FIGS. 3 and 4 , the first substrate of the present embodiment comprises: plural gate lines 3121 substantially parallel to each other; plural data lines 3122 substantially parallel to each other and crossing the gate lines 3121; plural switch units 3123 respectively electrically connecting to the gate lines 3121 and the data lines 3122; and plural pixel electrodes 3151 respectively disposed in a region defined by the gate lines 3121 and the data lines 3122 and electrically connecting to the switch units 3123. In addition, the first substrate further comprises: a second insulating layer 3124, disposed over the switch units 3123 of the TFT layer 312 and having contact vias 3124 a to expose a part of the switch units 3123, i.e. drain electrodes 3123 d of the switch units 3123.

Herein, the pixel electrode of the present embodiment has specific shapes to improve the liquid-crystal efficiency as well as reduce the widths of the dark lines when the display panel is in a bright state. Hereinafter, the shape of the pixel electrode near to the contact via in the display panel of the present embodiment is illustrated in detail.

FIGS. 5 and 6 are respectively a schematic view of partial pixel electrode according to one embodiment. Herein, for clearly describing the features of the pixel electrode of the present embodiment, FIGS. 5 and 6 are the same views, and the difference therebetween is only the reference numbers. As shown in FIGS. 5 and 6 , the pixel electrode of the present embodiment comprises: a first finger portion 51 with a first inner edge 511 and a third outer edge 512 opposite to the first inner edge 511; a second finger portion 52 with a second inner edge 521 and a first outer edge 522 opposite to the second inner edge 521, wherein the second inner edge 521 is between the first inner edge 511 and the first outer edge 522; a contacting portion 53 electrically connecting to the switch unit 3123 (as shown in FIG. 4 ) through a contact via 3124 a, and a part of the contacting portion disposed in the contact via 3124 a to electrically connect to the drain electrodes 3123 d of the switch units 3123 (as shown in FIG. 4 ); a first bending portion 54 between the first finger portion 51 and the contacting portion 53, connecting the first finger portion 51 and the contacting portion 53, and having a third inner edge 541 and a fourth outer edge 542 opposite to the third inner edge 541; and a second bending portion 55 between the second finger portion 52 and the contacting portion 53, connecting the second finger portion 52 and the contacting portion 53, and having a fourth inner edge 551 and a second outer edge 552 opposite to the fourth inner edge 551, wherein the fourth inner edge 551 is between the third inner edge 541 and the second outer edge 552.

As shown in FIG. 5 , in the pixel electrode of the display panel of the present embodiment, a first angle θ1 included between a first extension line of the first inner edge 511 and the third inner edge 541 is smaller than a second angle θ2 included between a second extension line of the first outer edge 522 and the second outer edge 552. In addition, as shown in FIG. 6 , a first acute angle θa included between the third inner edge 541 and a reference line parallel to a first direction X is greater than a second acute angle θb included between the second outer edge 552 and the reference line, and the first direction X is substantially parallel to a gate-line-extending direction(as shown in FIG. 3 ). When the first angle θ1 is smaller than the second angle θ2 and/or the first acute angle θa is greater than the second acute angle θb, the second outer edge 552 can be more close to the third inner edge 541, so that the dark lines existing when the display panel in the bright state can be more close to the region near to the contacting portion 53, resulting in the improvement on the liquid-crystal efficiency. In the present embodiment, a difference between the first angle θ1 and the second angle θ2 is in a range from 1 degree to 10 degree; and a difference between the first acute angle θa and the second acute angle θb is also in a range from 1 degree to 10 degree. Herein, the phrase “the first direction is substantially parallel to a gate-line-extending direction” refers to that an included angle between the first direction and the extension direction of the gate line is 0-5 degree, and most preferably is 0 degree. In addition, the term “first acute angle” and “second acute angle” refers to included angles ranging between 0 degree and 90 degree.

In addition, as shown in FIG. 5 , in the pixel electrode of the display panel of the present embodiment, the second finger portion 52 has a first width W1 along the first direction X, the second bending portion 55 has a second width W2 along the first direction X, and the first width W1 is greater than the second width W2. Similarly, when the first width W1 is designed to be greater than the second width W2, the width of the second bending portion 55 near to the contacting portion 53 can be reduced, further reducing the width of the dark lines existing when the display panel is in a bright state.

Furthermore, as shown in FIG. 5 , in the pixel electrode of the display panel of the present embodiment, a finger portion gap 57 is between the first inner edge 511 and the second inner edge 521, a bending portion gap 56 is between the third inner edge 541 and the fourth inner edge 551, and the bending portion gap 56 is between the finger portion gap 57 and the contacting portion 53 and connects the finger portion gap 57 and the contacting portion 53. Herein, the second bending portion 55 has a first length L1 along a second direction Y, the bending portion gap 56 has a second length L2 along the second direction Y, the second direction Y is substantially vertical to a gate-line-extending direction(as shown in FIG. 3 ), and the first length L1 is substantially equal to the second length L2. Herein, the phrase “the second direction is substantially vertical to a gate-line-extending direction” refers to that an included angle between the second direction and the extension direction of the gate line is 85-90 degree, and most preferably is 90 degree. In addition, the phrase “the first length is substantially equal to the second length” refers to that the deviation between the first length and the second length is 0-5%.

In addition, as shown in FIG. 5 , in the pixel electrode of the display panel of the present embodiment, the finger portion gap 57 has a third width W3 along the first direction X, the bending portion gap 56 has a fourth width W4 along the first direction X, and the third width W3 is smaller than the fourth width W4. Similarly, when the third width W3 is designed to be smaller than the fourth width W4, the width of the second bending portion 55 near to the contacting portion 53 can be reduced to further reduce the width of the dark lines existing when the display panel is in a bright state.

As shown in FIG. 6 , in the pixel electrode of the display panel of the present embodiment, there is a first distance D1 from the first outer edge 522 to the third outer edge 512 along the first direction X, the contacting portion 53 has a fifth width W5 along the first direction X, and the first distance D1 is smaller than the fifth width W5. In addition, there is a second distance D2 from the second outer edge 552 to the fourth outer edge 542 along the first direction X, and the second distance D2 is smaller than the fifth width W5. In order to achieve the purpose of high pixel density, the area of one single pixel region has to be decreased; however, the contact via 3124 a therein cannot be reduced at the same time. Hence, in order to prevent the problem that the dark line near to the contacting portion 53 and the second bending portion 55 may exist due to the various tilt directions of the liquid crystal molecules, the first distance D1 and the second distance D2 are designed to be respectively smaller than the fifth width W5. Therefore, when the display panel is in a bright state, the dark line can be more close to the region near to the contacting portion 53, further improving the liquid-crystal efficiency in this region.

Furthermore, as shown in FIG. 6 , in the pixel electrode of the display panel of the present embodiment, the first distance D1 is also designed to the greater than the second distance D2. Hence, the width of the second bending portion 55 near to the contacting portion 53 can be decreased, to further reduce the dark line existing when the display panel is in a bright state.

The display panel shown in FIG. 2 is examined to confirm the display panel provided by the aforementioned embodiment has better liquid-crystal efficiency. In addition, the liquid-crystal efficiency, when there are various differences between the first angle θ1 and the second angle θ2 of the pixel electrode shown in FIG. 5 , is also measured. Herein, the term “the liquid-crystal efficiency” refers to the light intensity per unit area.

When a driving voltage ranging from 0 V to 8 V is applied to the display panel shown in FIG. 2 , the liquid-crystal efficiency are measured in the case that the first angle θ1 and the second angle θ2 of the pixel electrode are the same (the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 0 degree) and the differences between the first angle θ1 and the second angle θ2 of the pixel electrode are 2, 3, 4 and 5 degree. The obtained liquid-crystal efficiency in the region shown in FIG. 5 is illustrated in FIG. 7 . When the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 0 degree, the obtained liquid-crystal efficiency in the region shown in FIG. 5 is 0.048643%. When the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 5 degree, the obtained liquid-crystal efficiency in the region shown in FIG. 5 is 0.051924%. Comparing the case that the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 0 degree, the gain of the liquid-crystal efficiency when the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 5 degree is 6.75%. This result indicates that the liquid-crystal efficiency in the region shown in FIG. 5 can be improved when the width of the second bending portion 55 is reduced to make the first angle θ1 smaller than the second angle θ2, that is, the second outer edge 552 is getting more close to the first bending portion 54.

Herein, the pattern of the dark line corresponding to the pixel electrode shown in FIG. 5 when the display panel is in a bright state is simulated. The result is shown in FIG. 8 , in which the display panel shown in FIG. 2 is used for the simulation, wherein the first angle θ1 and the second angle θ2 of the pixel electrode are the same (the difference between the first angle θ1 and the second angle θ2 of the pixel electrode is 0 degree), and the first angle θ1 is smaller than the second angle θ2 of the pixel electrode and the difference between the first angle θ1 and the second angle θ2 is 5 degree.

As shown in FIG. 8 , comparing the case that the first angle θ1 is identical to the second angle θ2 of the pixel electrode, on the basis of the same reference line (indicated by the dot line) which is substantially parallel to the first direction X being a gate-line-extending direction (as shown in FIG. 3 ), the width of the dark line can be significantly reduced (indicated by the arrows) when the difference between the first angle θ1 and the second angle θ2 thereof is 5 degree. Thus, the stability of the liquid crystal molecules in this region can be improved.

In conclusion, in the aforementioned embodiment, the second outer edge of the second bending portion can be more close to the fourth inner edge thereof and the third inner edge of the first bending portion when the first angle is designed to be smaller than the second angle. Therefore, when the display panel is in a bright state, the width of the dark line corresponding to the pixel electrode can be reduced, and also the dark line can be getting more close to the region near to the contacting portion, resulting in the liquid-crystal efficiency improved.

In the aforementioned embodiment, the tem "width", "distance" and "length" respectively refers to "minimum width", "minimum distance" and "minimum length" between two edges, and the “angle” refers to "maximum angle" included between two edges, extension lines thereof and/or reference lines.

In the aforementioned embodiment, the pixel electrode comprising two finger portions and bending portions are described. However, in other embodiment of the present invention, the pixel electrode may comprise three or more finger portions and bending portions, as long as the finger portions and bending portions most far from the TFT unit (which is the right finger portions and bending portions in the view of FIG. 3 ) has the aforementioned features.

In addition, in the aforementioned embodiment, a homogeneous aligned display panel is described. However, in other embodiment of the present invention, vertical aligned display panel may also have the aforementioned features of the present invention.

Furthermore, the display panel provided by the aforementioned embodiment may be used with any touch panel known in the art, to form a touch display device. Meanwhile, the display panel provided by the aforementioned embodiment and the touch display device can be applied to any electronic device for displaying images, such as a mobile phone, a notebook, a camera, a video camera, a music player, a navigation system, or a television.

Although the invention has been explained in relation to its embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed. 

What is claimed is:
 1. A display device, comprising: a gate line having an extension direction; a switch unit electrically connecting to the gate line; a pixel electrode electrically connecting to the switch unit; and a slit in the pixel electrode, wherein a virtual line parallel to the extension direction passes through an end point of the slit which is closest to the gate line, the pixel electrode is divided into a first portion and a second portion by the virtual line, and the first portion is closer to the gate line than the second portion, and wherein the slit has a first width in the extension direction and a second width in the extension direction, the second width is closer to the first portion than the first width, and the first width is less than the second width.
 2. The display device of claim 1, wherein the pixel electrode has two curved edges near to the gate line.
 3. The display device of claim 2, wherein at least one of the two curved edges is not overlapped with the gate line.
 4. The display device of claim 1, wherein an end of the slit has a curved shape.
 5. The display device of claim 1, wherein the second width is a maximum width.
 6. The display device of claim 1, wherein the first portion is at least partially overlapped with the switch unit.
 7. The display device of claim 1, further comprising: an insulating layer disposed over the switch unit and having a contact via.
 8. The display device of claim 7, wherein the first portion of the pixel electrode and the contact via are at least partially overlapped.
 9. The display device of claim 7, wherein a part of the first portion of the pixel electrode is disposed in the contact via.
 10. The display device of claim 7, wherein the first portion of the pixel electrode is electrically connected to the switch unit through the contact via. 